This invention relates in general to constant velocity joints and in particular to an improved structure for a flexible boot assembly adapted to protectively cover a constant velocity joint.
In most land vehicles in use today, a driveshaft assembly is provided for transmitting rotational power from an output shaft of an engine/transmission assembly to an input shaft of an axle assembly so as to rotatably drive one or more wheels of the vehicle. A typical driveshaft assembly includes a hollow cylindrical driveshaft tube having first and second universal joints connected to the ends thereof. The first universal joint is connected between the output shaft of the engine/transmission assembly and the first end of the driveshaft tube, while the second universal joint is connected between the second end of the driveshaft tube and the input shaft of the axle assembly. The universal joints provide a rotational driving connection from the output shaft of the engine/transmission assembly through the driveshaft tube to the input shaft of the axle assembly, while accommodating a limited amount of misalignment between the rotational axes of these three shafts.
Universal joints are commonly classified by their operating characteristics. One important operating characteristic relates to the relationship between the instantaneous angular velocities of the two shafts that are connected together through the universal joint. In a constant velocity type of universal joint, the instantaneous angular velocities of the two shafts are always equal, regardless of the relative angle at which the two shafts are oriented. In a non-constant velocity type of universal joint, the instantaneous angular velocities of the two shafts may vary with this relative angle, although the average angular velocities for one complete rotation are equal.
A typical structure for a constant velocity joint includes a hollow outer race that is connected to one of the shafts and an inner race disposed within the outer race that is connected to the other of the shafts. The inner surface of the outer race and the outer surface of the inner race have respective pluralities of grooves formed therein. Each groove formed in the inner surface of the outer race is associated with a corresponding groove formed in the outer surface of the inner race, and a ball is disposed in each of the associate pairs of grooves. The balls provide a driving connection between the outer and inner races such that rotation of one of the one of the shafts results in rotation of the outer race, the inner race, and the other of the shafts. An annular cage is typically provided between the outer and inner races for retaining the balls in the grooves. The cage is provided with a plurality of circumferentially spaced openings for receiving and retaining the balls.
In order to protectively cover the various components of the constant velocity joint from dirt, water, and other contaminants, and further to retain an adequate amount of lubricant therein, it is known to provide a flexible boot thereabout. A typical flexible boot includes a first relatively large end that is secured to the outer race of the constant velocity joint and a second relatively small end that is secured to the shaft extending from the inner race of the constant velocity joint. Usually, the boot is formed from a rubber or plastic material having a plurality of bellows-shaped convolutions formed therein to accommodate angular movement of the shaft relative to the outer race. When installed about the constant velocity joint, the flexible boot functions to protectively cover the various components of the constant velocity joint from dirt, water, and other contaminants, and further to retain an adequate amount of lubricant therein.
Several structures are known in the art for securing the ends of the flexible boot to the associated components of the constant velocity joint. Typically, the relatively small end of the flexible boot is secured to the shaft extending from the inner race of the constant velocity joint by an annular band clamp. The band clamp extends concentrically about the co-axially overlapping portions of the flexible boot and the shaft so as to frictionally retain the relatively small end of the flexible boot thereon. In some instances, the relatively large end of the flexible boot is secured to the outer circumferential surface of the outer race of the constant velocity joint in a similar manner. Alternatively, it is known to secure the relatively large end of the flexible boot to an axial face of the outer race using an annular retaining ring and a plurality of threaded fasteners. Although both of these structures function satisfactorily, it has been found that they may undesirably limit the maximum operating angles accommodated by the constant velocity joint in some instances. Thus, it would be desirable to provide an improved structure for a flexible boot assembly adapted to protectively cover a constant velocity joint.
This invention relates to an improved structure for a flexible boot assembly adapted to protectively cover a constant velocity joint. In a first embodiment of the invention, the boot assembly includes a flexible boot having an end portion that is molded about a flange portion of a rigid can. The flexible boot is preferably formed from an elastomeric material and can be integrally molded to a metallic can by an insert molding or other similar process. The metallic can includes a hollow cylindrical flange portion for positioning the can with respect to the constant velocity joint. The metallic can also includes a face portion having a plurality of apertures formed therethrough for mounting the boot assembly to the constant velocity joint. The inner surface of the metallic can includes a bead of a sealing material or a gasket for sealingly engaging the boot assembly to the adjacent face of the constant velocity joint. In another embodiment, the entire boot assembly is formed by using elastomeric material. In a second embodiment, the entire boot assembly is formed from an elastomeric material. The boot assembly may or may not include the hollow cylindrical flange portion for positioning it with respect to the constant velocity joint.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.